segment: fix offset handling with non 0 start

The position in the segment is relative to the start but the offset
isn't, so subtract the start from the position when setting the offset.
Add unit test for this as well.

1 files changed, 1 insertions, 1 deletions

diff --git a/gst/gstsegment.c b/gst/gstsegment.c
index fc52363f8..2f1b037ad 100644
--- a/gst/gstsegment.c
+++ b/gst/gstsegment.c
@@ -757,7 +757,7 @@ gst_segment_offset_running_time (GstSegment * segment, GstFormat format,
       if (position == -1)
         return FALSE;
 
-      segment->offset = position;
+      segment->offset = position - segment->start;
     }
   }
   return TRUE;